Conventionally, as a technique related to a ballpoint pen capable of writing drawn lines having different widths using one writing shaft, as disclosed in Patent Literature 1, a technique of controlling the amount of ink leakage using a pressurizing mechanism provided in a rear end portion in a shaft tube to change a width and a thickness of a drawn line is known.
Moreover, as disclosed in Patent Literature 2, a technique of changing the width and thickness of drawn lines using a ballpoint pen in which pen tips having different ball diameters are attached to both ends of a writing shaft is also known.
Moreover, conventionally, as a technique related to a ballpoint pen capable of writing drawn lines having different widths using one writing tip, as disclosed in Patent Literature 3, a technique of providing a spring inside a holder so that a writing ball is always pressed toward the writing tip by the resilience of the spring and allowing lines of different widths to be drawn according to a writing load is known. Moreover, a writing instrument capable of moving a marking surface portion back and forth and writing a plurality of narrow and bold lines is also disclosed.